Hey it's me i finnaly have a engine combo and wanted to see what yall thought about it. Vortec Head's, Performer RPM Intake, Comp Cam's Xtreme Energy Hydraulic Roller Camshaft, dur.@50 242/248, lift 540/562, lobe separation 110, RPM range, 2,800 to 6,000 , 3000 stall torque converter. and 3:73 gear's


P.S. I will be having the head's ported and polish'ed

post any coment's or recomendation's you have

 

Whare you doing about springs on the Vortecs?

 

I will have what ever work done to the vortec's for them to except the cam. I just forgot to put that down

 

I think you have too much duration on that cam. With a 110 degree lsa and 242/248 duration you will probably need a vacuum can and it will idle horribly if it’s going in a 350. Remember, with cams bigger is not always better. Like lingenfelter says, great heads and a moderate cam will always make more power than a huge cam with ok heads.

I don't think that the vortecs 170cc intake runners will be big enough to support a 350 spinning at ~6000rpm. If you do run that cam you are probably not interested in emissions so I would look at the Pro Topline Iron heads. These are what I am going with for my next engine, you can get them assembled for around 800 and they will flow 260 cfm @.500 intake (vortecs flow 228cfm @.500).

 

i like the sound when they idle rough and im tired of having a car with all it's power on the bottom end i kick peoples butt on the low end but they allway's out pull me up top. The reason i picked that cam was because of the RPM range the 2800 to 6000 RPM range. Their is a cam witch is one step below that. It's a 236/242 Dur @ 50, the lift is 520/540, 110 lsa, 2,500 to 6,000 RPM range

 

I agree with JR305. You are going to have a mismatch between the heads and the cam. If you do decide to stick with that power band you'll need a manual or a 3500 stall converter. It may race better, but ask yourself how often you are turning over 2500 RPM 'cause it's going to drive crappy below that. I realize the 3.73's will raise your RPM in lower gears but once you're cruising, you'll be well below your torque range.

 

The vortec heads are a waste of money if you're looking to run that big of a cam. Fastburn heads would be a better choice. Cheaper and weight less while flowing more air with the higher lift cam.
Keep vortec heads with lift under 480 for stock or if you get them worked over for larger springs and lift, still don't go more than 550 with a relatively low duration. It's a catch 22. Sure vortec heads are great but they're only great with parts that match well with the relatively awesome flow ratings with lift under 500. Just my opinion.
Vortec heads seem to have a limit of the Lt4 hotcam, anything more and it just doesn't make the power of a larger port head like the fastburns or anything with at least 190cc intake runners (aftermarket of course).

 

Can yall please recomend me a combo then please

 

Here is the combo I am going to be building over the next few weeks on a 350.

Pro Topline Iron heads 200cc intake runners, 64cc chambers.
Cam specs: 224/230 .503/.510 112 but with 1.6rr.

I will be running the holley stealth ram intake though. I have done tons of research on this cam and heads. Peak power should be around 6000 shifting around 6300rpm. The cam should have a little lope to it and should bull decent vacuum at idle. I have found dyno charts with a combo similar to mine, except with a slightly smaller cam that made 380rwhp @ around 6000rpm.

 

What about piston's and stuff like that. Plus can you give me a link for the head's and cam. Thank's for all the help man

 

I will be using Hypereutectic pistons. I am not to sure how much power and rpm the stock rotating assembly can take.

Heads
cam (second one from the top)

I don't want to start a TBI debate, but I don't think the Holley 670 will support this combo. I just got off the phone with proshaver and he is selling the Pro Topline iron heads for just under 900 assembled. That’s with the K3 assembly package (what you need to run this cam)

 

JR305 is correct again on questioning the Holley TBI. It surprises me how many people post which cam and combo they're gonna use to get xxx HP, but overlook the TBI system. Regardless of cam and heads:

http://www.rceng.com/technical.htm

To get 350 hp will require 220 pph fuel flow. If you've got 2 injectors, that means 110 pph each. Seen any of those lately? No, but we can bump the pressure 50% from 11psi to 16psi.
Sure, bigger injectors and more pressure will ALLOW more hp but they will absolutely require chip tuning to be driveable and, remember, the chip tuning will not make any more hp than the injector/pressure combination allows. It'll just allow it to be manageable at less than WOT conditions.

One of the best combinations I've seen for cost and results would be Vortec or Torquer heads with a used Lt1 cam. The Vortecs will require a manifold conversion but cost a little less, so how much do you want to spend? If price is nothing, why stick with the 305?

NM, just saw your 355.

Regardless, go ahead with the gear change to either 3.42 or 3.73

 

Problem is, we have no real build-ups to base combo recommendations for you. Sure there's been tons of magazine buildups with different heads, cams and intakes but they all are dyno'd with carbs. Doing a buildup with the parts above would be treading in a somewhat unknown territory, where most people would just switch to a carb; others to MPFI. The above combinations are good guesses as to what to match to a TBI unit to make good power. It really all comes down to trying it to see if it works. You're the mule.

 

i agree with the earlier post about matching the cam to the heads. you also have to match the cam and heads to the induction system. the point earlier about the hp/fuel flow requirements is absolutely true. with stock fuel pressure, the best you're going to get is 180 pph (2 90 pph injectors).

questions: what's the max fuel pressure you can run with tbi, how many pph will that flow with 90 pph injectors, and what does raised fuel pressure do to mileage?

also, does gm or anyone else make injectors bigger than 90 pph that will work in tbi?

the next question is about airflow through the tbi unit. awhile back i read something about 2 bbl (and tbi) cfm and 4 bbl cfm being calculated based on different criteria, so your 670 tbi unit won't actually flow as much air as a 600 holley carb, and the cfm/cubic inches formula won't necessarily apply.

can anyone clear that up for me? also, if you use the criteria applied to cfm for a 4bbl, how much air actually flows through 305, 454 and holley 670 tbi units?

i read another post awhile back from someone running a 400 with a 454 tbi, but he'd bored it out to use 53mm throttle blades! how in the world do you get that to fit onto an intake?

i've been trying to learn as much as i could before i started messing with my 305 tbi. so far, it looks like the only way to stay with a tbi is to stay under 350 hp (because of fuel limitations) and 350 cubic inches (due to airflow restrictions), although the 454 tbi trucks would seem to fly in the face of that logic.

the vortec heads seem to be a great choice for tbi, as they make gobs of torque and operate best at lower rpms. the airflow / cubic inch limitations of the tbi directly correlate to max rpm. the higher you plan on revving, the more air it'll have to flow. for a street engine, more cubic inches with lots of torque and max hp at lower rpms means one fast car, but you can go too far.

this month's super chevy features a 383 buildup that made 530 hp and 500 lbs ft torque. they brag about the engine making 400 ft lbs of torque at only 2,000 rpm, but later admit that it spins the tires a lot. if you plan on running street tires, that much torque in that low rpm range make the car virtually useless for anything except turning tires into smoke!

to me, the challenge of building a fast tbi street car would seem to be to have a LOT of torque, make all your hp and torque at under 5,500 rpm, yet limit off-idle and low end torque so it'll hook up.

with that narrow of a torque "sweet spot", you'd have to throw the logic of using torque to pull through high gears and a wide-ratio transmission and run at least a 3.42, maybe even a 3.73 with a t-56.

i believe you'd also need a single plane vs. a dual plane intake and 1 3/4 vs. 1/58 headers to cut that low end torque. cam selection would be a bitch. if you jack up the duration to cut low end torque, you'll kill low end vacuum as well, which the tbi needs for the computer to work.

what do you guys think?

 

Aye. I dont see many times from guys with 350s. JPrevost has his, but I dont really remember any other ones. Perhaps that's a good topic.

 

FWIW, my L05 combo has seen a best of 15.50 @ 87.xx, but that is in my 4400# Caprice which I shouldn't mention, as it's now against the "rules".

I'm currently working on adapting a 454 TBI. I have the TBI, 80# injectors and have bored the manifold to 2.03 inches. I installed and tuned a vacuum afpr last fall but haven't had a chance to get a 1320 ft time on it. I'm planning to install the 454 TBI with my 65# injectors first since I don't, yet, have programming skills. I'm hoping to recruit some programming help(hear that Kevin?) when I swap to 80#ers.

 

Hey jprevost what state do you live in anyway's and is there any body that lives around mo, AR. TN

 

The GM 90# injectors can handle lots of pressure... I know a guy who was running 26# on a set. I've heard stories of 40#+. According to a phone call I made to holley several years ago their injectors start having problems around 18 psi. They have changed their design since so it would be worth looking into. Its not a bad idea to run a port injection style fuel pressure regulator to keep your pressure low at idle and give you more at WOT when you need it. This will help with idle and part throttle tuning where a huge injector is hard to tune... acts like a FMU for blower applications.

The 2bbls are flowed at 3", the 4bbls at 1.5". I'm not sure of a way to convert the number... maybe the injector flow vs pressure equation?

53mm? 2" x 2.54 is 50.12... so were talking 2.9 mm?? Not a big difference size wise so I don’t see why it wouldn’t work... not sure if I'd waste my time though.

With EFI you can always tune out some timing to get the power to the ground.

I like TBI's that rev... I like TPI's for trailer pulling max low rpm torque. Short runners are not well suited to maximize torque.

The cam mentioned initially is way too big. Something like that 224-230 setup on a 350 mentioned earlier is about as big as you want to go w/o going into alpha N tuning. Smaller on a 305. You really need to keep about 11"+ vac at idle to have enough resolution to tune it. A good flowing head doesn’t need a huge cam to make power anyway. Any lift beyond the heads peak flow number are also kind of a waste... if your heads peak flow is at .480 and you lift to .530 you are just wearing out valve springs quicker.

I really like vortec heads. They give more bang than many aftermarket heads for roughly 1/2 the buck. Just make sure you buy the correct intake for them and make sure you get them machined for and get valve springs for your added lift.